They’re only about the size of our Solar System, but they shine brighter than 100 galaxies combined. What are they? They’re quasars, and they may be windows into the beginning of our universe.

Q: What are quasars?
A: Quasars are small objects, probably formed when two galaxies collide. One galaxy forms a black hole in the other galaxy, and the black hole captures stars, dust, and gas. Temperatures inside the black hole reach millions of degrees, and large amounts of radiation are given off by the black hole.

Q: Why are they called quasars?
A: Astronomers first called them “quasi-stellar radio sources,” because some were observed with radio telescopes. However, not all quasars emit radio waves. They may also emit visible light, X-rays, infrared and ultraviolet radiation, and gamma rays. Now they’re called “quasars,” a shortened form of their original name.

Q: How long do quasars last?
A: Scientists think galaxies only act as quasars early in their lives. However, this phase would still last for billions of years.

Q: Who discovered quasars?
A: Astronomer Alan Sandage discovered quasars in the 1960s. He was photographing the sky, and noticed a star that didn’t act like stars usually do. In 1962, another astronomer, Maarten Schmidt, observed a quasar, and determined that it could not be a star. He discovered that the object was 2 billion light-years away. At this distance, a small would be too small to be seen on Earth. The object had to be something much larger, like a galaxy.

Q: Why are quasars so important to astronomers?
A: Quasars are important because they show us what the universe was like billions of years ago. The light from quasars takes billions of years to reach us. When we look at a quasar, we see what they looked like in the distant past. Because other galaxies, even our own, may have been quasars once, we can see what the universe was like long ago.